Variable output pump



y 1948- H. A. GARTWRIGHT VARIABLE OUTPUT PUMP Filed Sept. 24, 1943 2 Shqts-Sheet 1 y 1948- H. A. CARTWRIGHT 2,4455% VARIABLE OUTPUT PUMP Filed Sept. 24, 1943 2 Sheets-Sheet 2 I & .1@ .27

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Patented July 20,1948

UNITED STATES PATENT OFFICE 6 Claims. 1

This invention relates to pumps and, more particularly, to that class of pumps in which a variable fluid output is obtainable.

It is an object of the present invention to provide a pump having a plurality of fluid outlets and wherein means are provided for varying the flow of fluid under pump pressures through said outlets.

It is another object of the invention to provide a pump having spaced sets of rotatable gear type impellers, one set of impellers being positively driven while the other set is adapted to be rotated by fluid pressures developed by the operation of the first set, and wherein improved mechanism is provided, susceptible to manual control, for causing one set of impeller to rotate at a diflerent rate of speed than the other.

A further object of .the invention is to provide a pump of the character set forth wherein the pump casing between the spaced sets of impellers is provided with a valve controlled outlet and, also, with an independent outlet communicating with the discharge sides of the fluid-rotated impellers, so that by causing th fluid-rotated impellers to revolve at a difierent rate of speed than that of the power-operated impellers, control is embodiment of the invention illustrated, comprises a central casting ll having marginal flanges I! to which are bolted, or otherwise secured, spaced vertical side plates l3 and H. Internally, the casing is formed to provide s, pair of impeller chambers l5 and it, which are partly separated by a vertical divisional wall I I, the latter terminating above the bottom of the easing so that said chambers are in relative communication. The side plate I 3 is formed with a. fluid-inlet extension IS, the latter being joined with a pipeline l9 leading to a, source of fluid supply, such as a tank indicated at 20. The extension communicates with a pocket 2|, formed at the right side of the casing, as the latter is viewed in Fig. 2.

In registration with the chamber ii, the side 1 plates l3 and H are provided with bearings 22 obtained over the volumes of fluid caused to pass through said outlets.

With these and other objects in view, the in vention consists in the novel features of construction, combinations of elements and arrangements of parts, hereinafter more fully described and pointed out in the appended claims,

In the accompanying drawings:

Fig. l is a horizontal sectional view taken through a variable output pump formed in accordance with the present invention, the plane of the figure being indicated by the line II of Fig. 2;

Fig. 2 is a vertical transverse sectional view taken on'the plane indicated by the line II--II of Fig.1;

Fig. 3 is a vertical longitudinal sectional view taken through the pump on the plane indicated by the line III-III of Fig. 1;

Fig. 4 is a. vertical sectional view on the line IV--IV of Fig. 1;

Fig. 5 is a detail transverse-sectional view of the shifting fork control for the friction wheel;

Fig. 6 is a diagrammatic view disclosing fluid flow paths through the pump and associated piping.

Referring more particularly to the drawings, the numeral Ill designates the impeller casing of my improved pump, This casing, in the specific for the reception of impeller shafts 23, The upper of these shafts extends through a packing 24 to the exterior of the casing in order that it may be connected with a source of rotating power,

such as an electric motor, or the power take-oil? of an automotive truck vehicle. Rotatable with the shafts 23 and adapted to occupy the chamber I5 is the primary or driving set of fluid-displacing impellers 25. Advantageously, these impellers may be of the intermeshing gear type having interfitting helical teeth, as indicated at 26.

A duplieative secondary or driven set of impellers 21 is located in the chamber I 6 and are rotatably supported by shafts 28 journaled as at 29 in bearings provided in the side plates l3 and M. The impellers 21 are arranged in parallel relationship with the primary impellers 25 and are separated from the latter by the divisional wall ll. If the impellers 21 were free to rotate, the same would be revolved by the pressure of fluids displaced by the primary impellers, and the fluid discharged from the impellers 21 would pass through an outlet pocket 30, provided in the walls of the casing ill on the opposite side of the latter as regards the pocket 2|, the pocket 30 being in communication with the fluid return pipe 3| leading to the fluid tank or other source of fluid supply 20.

In addition to the outlet provided by the pocket 30 and the return pipe 3|, the pump i provided with a second outlet port 32. This port is arranged in the bottom of the casing M in communication with the chambers l5 and I6 and between the two sets of impellers 25 and 21. Normally, the port 32 is closed by a valve 33, which is pressed by a spring or other loading element II, the valve 33 being referred to hereinafter as the 3 pressure valve. When the driven impellers 21 rotat at approximately the same rate of speed as the driving impellers 25, all fluid delivered to the pump is discharged through the return pipe 3|. However, when the driven impellers 21 rotate at a lower rate of speed than the driving impellers, fluid pressure is built up in the chamber space formed between said impellers, which cause the pressure valve to open, diverting fluid flow from the return pipe 3| and allowing such flow through the port 32. If rotation of the driven impellers 21 should be completely arrested, then all fluid flow from the pump takes place through the port 32, The amount of fluid flow through the port 32 is thus proportional to the relative R. P. M. of the driving anddriven sets ofimpellers. Below the port 32, the casing may be provided with a fluid outlet box 35 with which communicates pipe lines 36 and 31, the latter being each provided with a. control valve. shown at 38 and 38a. The lines 36 and 31 may extend to any lnstrumentallty to which fluid is to be applied under pressure in varying amounts, the bottom of the box 35 being formed with a removable plug 39, providing access to the spring 34 and the valve 33.

To provide for different rotational speeds between the two sets of impellers, the upper of the shafts 23 extends through a packed bearing 48 provided in the side plate H and has fixed to its outer end the hub of a vertically positioned rotating disk 4|. Engaging with the working face of this disk is a radially adjustable friction wheel 42 which is longitudinally adjustable on a splined worm shaft 43. One end of the shaft 43 may, for illustration, be rotatably received within a bearing 44 provided in the outer end of a bracket 45 extending from the casing l0, while the opposite end portion of said shaft may be rotatably received within a bearing 46 provided in connection with the walls of a gear housing 41, the latter being supported in any suitable manner from the casing Hi, as by the use of a bracket extension 48.

To adjust the friction wheel longitudinally of the shaft 43, and radially of the working face of the disk 4 I, any suitable control may be utilized. In the present illustration, I have disclosed this control as being of a manual character, although power operated or automatic means may be used if desired. A convenient control consists in providing the annularly grooved hub 49 of the wheel 42 with a, loose ring 50 from which project studs 5| which are adapted to be received within slots 52 provided in the forked end 53 of a shifting lever 54. The upper end of this lever is flxedto a rock shaft 55 which carries a worm gear 56. This gear meshes with a worm 51 fixed on a manually rotated shaft 58. The latter is journaled in a bearing provided in an upstanding bracket 59 suitably connected with the pump casing,and the outer end of the shaft 58 is equipped with a hand wheel 60. By rotating the wheel 66, oscillatory motion may be imparted to the lever 54 in order to move the friction wheel to a desired operating position on the face of the disk 4|, the worm and worm gearing serving to maintain the shifting lever and the wheel 42 in their various positions of adjustment.

The end of the shaft 43 which projects into the housing 41 has fixed thereto a worm 6|, which meshes with a worm gear 62. This gear is loosely mounted for rotation on the outer end of the upper of the driven impeller shafts 28. Formed with or fixed to the gear 62 is a plain gear wheel 63, which meshes with a pinion 64 loosely mounted for rotation on the lower of the shafts 23. Formed with or secured to the hub of the pinion 64 is an enlarged gear 65, the teeth of which mesh with a pinion 66 which is keyed or otherwise fastened as at 61 to the upper of the shafts 28.

From the foregoing, it will be seen that if the friction wheel 42 occupies a position in the center of its radial line of contact with the face of the disk 4|, the proportions of the drving mechanism between the driving and driven impellers will be such as to permit the driven impellers 21 to rotate at approximately one-half the number of revolutions per minute as the driving impellers 25. Under these conditions, approximately onehalf of the fluid discharged by the impellers 23 will pass through the pprt 32 and the other half through the return pipe 3|. If the friction wheel 42 should engage the axial center of the disk 4|, rotation of the shaft 43 is precluded so that the worm and worm gearing 6| and 62 will hold the shafts 28 of the driven impellers 21 against rotation, so that all the fluid acted upon by the primary impellers 25 will pass through the port 32. If the friction wheel 42 should contact the outer face of the disk 4| adjacent to its outer peripheral edge, the r tational speed imparted to the worm shaft 43 w i be such as to permit the driven impellers 21 to rotate at approximately the same rate of speed as the driving impellers 25. Under this lattercondition, the port 32 will be closed by the valve 33 and substantially all fluid dis-' placed by the impellers will be discharged from the pump casing through the return pipe 3| Proportiona-te conditions of fluid, discharge will take place when the friction wheel 42 occupies other positions in its engagement with the face of the disk 4|.

While my improved pump apparatus may be employed in many different capacities wherein a metered output of fluid operated upon by the pump is necessary or desired, I have found my improved apparatus particularly useful in delivering metered quantities of a fluid-like material to road or highway surfaces. In the treating of road surfaces, heated bituminous compounds are often sprayed in measured amounts thereon. This is most frequently performed by apparatus involving an automotive vehicle equipped with a tank in which the bituminous compounds are contained, together with associated heating and pumping equipment for forcing the compounds to an oriflced spray bar mounted on the rear of the vehicle.

customarily, the pump mechanism is operated from a. power take-oil shaft driven by the engine of the automotive vehicle, the amountof fluid I delivered to the spray bar being regulated by adjustable spring-loaded pressure valves. Such pressure valves are very inaccurate and unreliable in their operations, and, furthermore, it is difilcult to vary pump speed by use of a power takeoff, as the latter varies with the road speed of the vehicle or with changes produced by the changing Of gears in the engine transmission. Applications of asphalt are made with spray bars varying in length from 2 feet up to 24 feet. Also, the rate of application of the heated asphalt per square yard may vary from .05 gallon up to 2.0 gallons with fine graduations therebetween. Thus the ordinary gear ratio of an automotive vehicle does not supply this variation. By the use of the pump apparatus comprising the present invention, a very accurate and graduated control of the amount of the heated fluid delivered to the spray bar may be obtained.

The principal function of my improved pump is to be able to meter the fluid material accurately, so that the required quantity will pass to the outlet mechanism. The first set of impellers 25 pumps a metered amount from the supply tank and the secord set of impellers 21 subtracts a metered quantity of material from the original quantity pumped, leaving a metered amount for discharge onto the road. I

The valve 38ais preferably in the form of a three-way cock, having an extension which leads back to the return line 3|, so that material can be circulated back to the tank during heating, loading and circulating operations. The valves 38 and 38a do not affect the pump in any way but are part of my improved system of handling the material after it hasleft the pump proper. In Fig. 6, the spray bar has been indicated at H.

While I have illustrated and described what I now deem to be the preferred form of the present invention, nevertheless, it will be understood that the same is subject to considerable variation or modification and I therefore reserve the right to employ all such constructional departures that comewithin the scope of the following claims.

I claim:

1. A variable output pump comprisin a casing having an impeller-receiving chamber, a pair of rotatable power driven impellers mounted in said chamber, a secondary pair of impellers arranged in said chamber in spaced relation from said primary pair, a fluid inlet entering said chamber at one side of the primary impellers, a fluid outlet communicating with said chamber on the discharge side of the secondary impellers, gearing coacting with the secondary impellers to normally retain the latter against rotation, variable speed motion-transmitting means driven directly by one of the primary impellers for operating said gearing to admit of varying rotational speeds of the secondary impellers relative to the primary impellers from zero to one to one, a second fluid outlet disposed between said sets of impellers, and a pressure valve normally closing said second outlet.

2. .A variable output pump comprising a, casing formed with an internal impeller-receiving chamber, a fluid inlet communicating with one side of said chamber, a fluid outlet communicating with the other side of said chamber, spaced sets of driving and driven impellers rotatably mounted in said chamber between the fluid inlet and outlet, gearing coacting with thedriven impellers to normally retain the latter against rotation, variable speed motion transmitting means operated directly by the riving impellers for actuating said gearing, whereby to cause rotation of the driven impellers at speeds ranging between zero and one to one with respect to the driving impellers, a second fluid outlet communicating with said chamber between said sets of impellers, and a pressure valve normally closing said second outlet, said valve serving to open said second outlet when the rotational speed of the driven impellers is less than that of the driv ing impellers.

3. A dual outlet pump comprising a casing meshing driving impellers mounted for rotation in said chamber contiguous to its fluid inlet side, a complemental set of driven impellers mounted for rotation in said chamber adjacent to its fluid outlet side, a second fluid outlet communicating with said chamber between said driving and driven impellers, gearing coacting with the driven impellers to normally retain the latter against rotation, and manually controlled variable speed motion-transmitting means driven directly by one of said driving impellers for actuating said gearing to cause rotation of the driven impellers at speeds ranging between zero and one to one with respect to the driving impellers.

4. A dual outlet pump comprising a casing having an impeller-receiving chamber formed therein, a primary pair of rotatable power driven impellers mounted in said chamber, a secondary pair of impellers arranged in said chamber in parallel and spaced relation from the primary pair, a fluid inlet entering said chamber at one side of the primary impellers, a fluid outlet communicating with said chamber on the discharge side of the secondary impellers, a second fluid outlet communicating with said chamber between said primary and secondary impellers, worm gearing coacting with the secondary impellers to retain the latter against rotation, said gearing including an operating shaft, a friction wheel slidably mounted on said worm shaft for rotation in unison therewith, and a disk rotatable with one of said driving impellers against the working face of which said friction wheel has adjustable driving engagement.

5. A variable output pump comprising a casing having a pair of communicating impeller chambers, a set of intermeshing helical-toothed driving impellers mounted for' rotation in oneof said I chambers, a fluid inlet communicating with the formed internally with an impeller-receiving chamber, a fluid inlet communicating with said chamber on one side thereof, a fluid outlet communicating with said chamber on the side "thereof opposite to said inlet, a set of toothed intertering impellers,

chamber containing the drivin impellers, a complemental set of inter-meshing helical-toothed driven impellers mounted for rotation in the second of said chambers, a fluid return outlet communicating with the second of said chambers for the discharge of fluids acted upon by the driven impellers, a second fluidoutlet communicating with said chambers between said sets of impellers, a loaded valve normally closing said second outlet, worm gearing normally restraining the driven impellers against rotation, said worm gearing including a drive shaft, a disk fixed to rotate with one of said driving impellers, a friction wheel slidably mounted on the drive shaft of said worm gearin for rotation in unison therewith, said wheel having the peripheral edge thereof disposed in driving engagement with the working face of said disk, and means for adjusting said wheel longitudinally on said shaft and radially with respect to the working face of said disk.

6. A metering pump comprising a casing formed with an internal impeller-receiving chamber, the latter being provided with a fluid inlet and a spaced fluid outlet, a set of power driven pumpin impellers of the positive displacement intermeshing gear type rotatably mounted insaid chamber contiguous to said inlet, a similar set of metering impellers rotatably mounted in said chamber adjacent to said outlet, motion-transmitting gearing for driving said mesaid gearing being of a type which will hold said metering impellers against rotation under rotating forces applied thereto through fluid displacement by said pumping impellers, variable speed motion transmitting means driven directly by one of said pumping impellers for driving said motion-transmittin gearing at varying rates of speed relative to the pumping impellers, and a pressure actuated valve normally closing a relief outlet provided in said casing between said sets of impellers, said valve automatically opening when the fluid displaced by the pumping impellers is in excess of that displaced by the metering impellers.

HORACE A. CAR'I'WRIGHT.

REFERENCES CITED The following references are of record in the tile of this patent:

Number UNITED STATES PATENTS Name Date Black et a1 June 12, 191'! Underwood Apr. 25, 1922 Pool Dec. 18, 1923 Heller Sept. 4, 1934 Ray et al Feb. 2, 1937 Laird Feb. 15, 1938 Peterson Mar. 19, 1940 

